Soil-structure interaction in the seismic response of the isolated overcrossings of the A14 motorway section Cattolica-Senigallia

The effects of soil-structure interaction on the seismic response of isolated overcrossings are investigated by considering five real bridges that will be built along the A14 Motorway in the Marche Region. The dynamic and mechanical properties of the soils are obtained from a comprehensive geotechnical characterization. The seismic input is constituted by ten triplets of real accelerograms that are processed by a local response analyses to capture the site amplification effects and the free-field motions within the deposits. The soil-structure interaction effects are evaluated by comparing the seismic response of the structure with that obtained from a conventional fixed base model. As for the overall behaviour, analyses demonstrate that the isolated bridges are not sensitive to soil-structure interaction that do not modify the fundamental periods of the structures. Isolation units are also slightly sensitive to the soil structure interaction that increases deformations and forces of about 10% with respect to those obtained with fixed base models.